<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>ES的常量</title>
</head>
<body>
<script>
    const PI = 3.14;  // 1、常量声明时必须赋值
    // PI = 3.1415926;    // 2、常量的值是只读的不允许修改
    console.log(PI);
</script>
</body>
</html>